1. Field of the Invention
The present invention relates to a liquid crystal display device and a method for fabricating the same.
2. Discussion of the Related Art
In accordance with the development of a variety of portable electric appliances such as mobile communication terminals and notebook computers, the demand for flat panel display devices for application to such appliances is increasing. Liquid crystal display devices, plasma display panels, field emission display devices and light emitting diode display devices and the like are researched as the flat panel display devices.
Of the flat panel display devices, the application of liquid crystal display devices is expanding due to advantages such as development of mass-production technology, ease of driving, low power consumption and implementation of high image quality and wide screen.
A general liquid crystal display device includes a liquid crystal panel in which a lower substrate is joined to an upper substrate such that they face each other via a liquid crystal layer and a driving circuit to apply a driving voltage and signal to the liquid crystal panel. The liquid crystal display device controls transmittance of light passing through liquid crystal layers respectively provided in a plurality of cells (pixels) according to data voltage and thereby displays an image in response to the image signal.
FIG. 1 shows a related art liquid crystal display device.
Referring to FIG. 1, the related art liquid crystal display device includes a lower substrate 10 (TFT array substrate), an upper substrate 30 (color filter array substrate), a liquid crystal layer 20, an adhesive layer 40, an electrostatic discharge layer 50 and a polarizing film 60.
The lower substrate 10 includes a pixel array 14 formed on a lower glass substrate 12. The pixel array includes a thin film transistor (TFT) for switching the pixel, a common electrode and a pixel electrode.
The upper substrate 30 includes RGB color filters 34 formed on an upper glass substrate 32, black matrices 36 formed between the color filters 34 to prevent mix of colored light and an over-coat layer 38 for planarizing the upper substrate 30.
A liquid crystal layer 20 is formed between the lower substrate 10 and the upper substrate 30.
An electrostatic discharge layer (ESD layer) 40 made of indium tin oxide (ITO) is formed on the upper substrate 30. An adhesive layer 50 is formed on the electrostatic discharge layer 40 and a polarizing film 60 is formed thereon.
Regarding the related art liquid crystal display device including the configuration described above, static electricity may be generated during a cleaning operation or an operation of bonding the polarizing film 60 in the fabrication process, and static electricity may be generated during driving for image display. In order to remove static electricity, electrostatic discharge layer 50 is formed.
In this regard, ITO which is a material for the electrostatic discharge layer 50 has a disadvantage of low electrostatic discharge performance due to relative high resistance thereof. Specifically, static electricity that is not effectively discharged from the electrostatic discharge layer 50 permeates the black matrix 36, the over-coat layer 38 and an active area where pixels are formed, thus causing defects such as blur.